Damping and arresting-means for suspension systems



July 8, 1952 A. F. TURNER ETAL DAMPING AND ARRESTING MEANS FOR SUSPENSION SYSTEMS 3 Sheets$heet 1 Filed July 14, 1945 l ll llf l ll ARTHUR F. TURNER OSMA A.ULLRICH JR.

3nnentor5 Gttorneg July 8, 1952 A. F. TURNER ET AL DAMPING AND ARRESTING MEANS FOR SUSPENSION SYSTEMS 3 Sheets-Sheet 2 Filed July 14, 1945 ARTHUR F TURNER OSMAR A.ULI RICH JR. Zmnentors attorney y 8, 1952 A. F. TURNER ET AL 2,602,332

DAMPING AND ARRESTING MEANS FOR SUSPENSION SYSTEMS Filed July 14, 1945 3 Sheets-Sheet 3 OSMAR A.ULLR|CH JR.

'lNVENTORS ATTORNEY Patented July 8, 1952 UNITED PAT OFFICE DAMPING-AND*ARBESTING-MEANSEOB SUSPENSION SYSTEMS Arthur-- F; Turner, Brighton; and Osmar A; Ullrich; Ji'r,"Gates, N. .Y-L, assignors' to-Eausch &xL'omlLQpticaliGompany; Rochester, NI Yp a corporation-of'NewYork:

Applicationil 1 .13 4, 1945;,Seria1No;605,

This'invention relates toinstruments' embodying suspension systems and more particularly it has reference to means for'damping and/or arrestingthe movements of suspension systems.

Certain'typesof relative delicate measuring instruments embody a member such as alight-vane whichis suspended from a supportby* a filament suspension so that it may turn against the resistance of the filament when'acted upon by forces whichare related to the quantitie to be measured: Since the vane-is suspendedbya flexible suspension filament, it'willalso be-free tosW-ing like a pendulum from thesupport; Su'ch'pendulous movements of the-vane-;- whether'produced by" accidental jarring or other "vibrations, will interfere' with the functioning of Y the instrument since the vane of such an'instrument usually carries-a small reflector'which-directsa beam-of lig ht andcross hair image onto a suitable=scalea The undesired pend'ulous movementsof the vane *may, therefore, cause the-cross hair image onthe scale to oscillate erraticallyand prevent an accurate reading 'of the instrument.

One of the objects of-- ourinvention' is; to provide means for damping the pen'dulous movements of an instrument suspension device. Another object is to provide magnetiemeans for damping pendulous' movements of a member which is carried by a flexible suspension-device. A further object is to provide in an instrument ofth'e-typ'e described means for arresting and holding the suspended member so as to relieve the suspension device fromsupporting the member. These and other objects and advantages reside in certain novel" features of construction, arrangement, and combination of-' partsas will hereinafter be-moref'ully described and'po'int'ed outin' the appended-claims.

Referring to-the drawings:

Fig. 1 is a front view ofan instrument-embody in'g'our invention, with parts shown' in section;

Fig. 2 is-a rear view-thereof with parts'in sectiOll';

Fig; 3 is a schematic view showing the-operation-ofour damping'device; I

Fig. 4' is a fragmentary view, with parts in section, "showing the mechanism for lifting the vans and movingth'e magnets. I r

Fig; 5 is a detail showing the relation of the p'art'swhen the vane has be'enlifted.

Fig. 6 is a fragmentary view'taken online li -6 o'flFzi'g. 1. r

Fig. 7' is a sectionalview'takenon" line T-I' of 3 lll ig;- 8' is afra'gmentary' horizontal sectional view" showingithewindow in the casing.

A preferred embodiment of our invention is shown on the drawingsas appl-iedto-a highvac uum gauge of the Knudsen type. The general theoryand' construction of this gauge are described, forinstance; by =DuM;ond' andPickelsin vol. 6, Review of Scientific Instruments" 1935, pages 362-370. It is to be understood that our novel dampingv and vane arresting devices may beappliedto other types of instruments embodyingsuspension devices.- Our noveld'amping and vane: arresting devices are shown, on" the drawings, as applied to a well-knowntype of vacuum gauge comprising a cylindrical casing I0 which is closed, respectively, at'its upper-and lower ends by threaded caps Hand [2. Threaded intothe upper cap H is a conduit l3 which connects the gauge to the-vacuum system whose pressureis to be measured: I

Fixedly mountedon cap I2 is a tube M'which supports" at its pper end a plate l5. Rotatably mounted on plate i5 is a gear-wheel I6 which is in operative" engagement with a pinion IT- carried at the upper'endof shaft lflwhichextends upwardly through the-cap l2 and within the tube l4; Secured" within'an axial opening in gear Wheel liiby means of screw l 9 is the downwardly projecting rod- 20. To the lower end ofthe rod 213 is fixedly secured the suspension filament 2| which may be formed of any suitablematerial such as-a tungsten wire having a diameter of the order of 0.0006 inch. Thelower endof'the filament 2| is secured to a thin metal strip 22 which is centrally secured to a flat rectangular vane 123* formed of light material, such as" thin aluminum sheeting. It'will'be seen that thevane 23 is thereby freely suspen'dedfrom the lowerend of the rod Zll-by means of the flexible'filament 2 l-. The lower end of shaft I8 is secured to a tapered plug which is rotatably mounted with a vacuum-tightjoint in the bushing 25 extending through an opening in'the cap 12. It will be ap? parent, therefore, that the vane 23 may berotatably adjustedbyturningjthe p1ug24' beneath the e- Fixedly mounted to the lower' cap 12' are the spaced metal members. 26 and z'l'which are insulated from the cap I2 by:suita-ble' insulation bushings 28 Secured, respectively; .at theupper ends of the members, 26 and .21 are the heating coils 28' and 29 whose upper ends are attached, respectively, to metal stripstlland' 3] which are secured atv their upper, ends to metal plate [5. Electrical currentfrom a suitable source is'supplied to heat th coils by mean of the lead-in wires 33 and; 34;; Whenthe' heating'coils are en;- ergized', the gas molecules in-"the neighborhood of the coils become heated and the total force produced by the impact of these molecules on the light aluminum vane 23 varies with the pressure in the gauge. Accordingly, th impact of the gas molecules on the portions of the vane facing the coilswill cause the vane 23 to turn.

about the vertical axis of the filament 2|, and the amount of movement of the vane 23 will, therefore, give an indication of the pressure within the gauge. In order to damp the turning movement of the vane 23, the Knudsen gauge is customarily supplied with suitable magnetic damping means such as the permanent magnet 32. In order to measure the turning movements of the vane 23, light rays from a suitable source are focused by means of lens 36, through a window 36' mounted in the front of the casing l0, onto a small reflector 31 secured to the upper part of the front face of vane 23 and thence onto a suitable scale 38. Such an arrangement is shown schematically in Fig. 3. 7

Since the vane 23 is supported by the flexible filament suspension 2!, the vane 23 will not only be capable of turning about the vertical axis of the filament 2! but it will also be subject to pendulous movement which may be caused by accidentally jarring the instrument or by vibrations otherwise produced. Such pendulous movements of the vane are highly undesirable because they can give rise to a complicated motion of the vane to such an extent that the reflectedbeam of light moves erratically on the scale making an accurate reading of the cross hair position impossible. Such conditions would, therefore, render the gauge inoperative. Although this type of vacuum gauge has been known for many years, it has heretofore been regarded as a relatively delicate instrument which has been reserved for use in the laboratory under ideal conditions of freedom from vibration. We have found that the principle reason for this lies in the fact that the horizontal magnetic field, as heretofore utilized, is incapable of dampin the undesired pendulous motions of the vane. By means of our novel clamping device, we have greatly reduced the undesired pendulous movements of suspension systems, such as found in the Knudsen vacuum gauge, and have thereby rendered such delicate instruments useful under conditions wherein they would be subject to accidental jarring or vibration.

For damping the undesired pendulous'move stantially coincident with the axis of vane 23,.in-

tersects the central portion of the plate. A pair of permanent magnets 40 and M are mounted respectively, in opposed relation, above and below the metal plate 39. The magnets are supported by arms 42 secured to block 43 which is mounted to swing laterally about the pivot formed "by screw 43 threaded into block 44. We prefer to mount magnets 49 and M relatively close to each other soas to produce a sufficiently strong magis threaded to a short vertical tube 46 which fixedly supports the block 44 by means of set screw 41. Rotatably mounted, with a vacuum-tight joint, in the bushing 45 is a tapered plug 48 to which is secured the upwardly extending. shaft 49 by means of set screw 50. Secured to shaft 49 is an arm 5|, projecting through an opening 52 formed in tube 45, and having a pin 53 which extends into a slot 54 formed in block 43.

The upper end of tube 46 fixedly carries a bushing 55 to which is secured by screws 56 an upwardly extending, offset metal spring member 51. Securedto the upper end of spring 57 and extending laterally therefrom is a relatively rigid netic damping field. A bushing ;45, extending through an opening in the .bottom of cap I2,

arm 58 which extends through a central opening 59 formed in vane 23 and has its free end formed to encircle, but not touch, the metal strip 22.

A second relatively rigid arm 60 extends laterally from bushing 55 through the opening 59 in vane 23 with its free end also encircling the metal strip 7 22. The upper end of shaft 49 projects beyond the tube stand fixedly carries a cam member BI When the cam member. is in the position shown in Fig. 4, the arms 58 and Eli are out of engagement with the vane 23 so that the latter is free to move. When it is desired to arrest the movement of the vane 23 so as to relieve the filament 2| from carrying the weight of the vane, the cam'Bl is turned, by means of the plug 48 beneath the gauge, to the position indicated in Fig. 5. In this position the cam 61 urges the spring member 51 outwardly and thereby raises the arm 58 so as to lift the vane and thereby bring the two arms into firm engagement with the upper and lower edges of the opening 59 formed in vane 23. Since such upward movement of the vane 23 carries the plate -39 upwardly, it is necessary to swing the magnets laterally so they will not interfere as the plate 39 is moved upwardly when the vane is arrested. It will be apparent from the foregoing description that the magnets 40 and 4| are swung laterally just before the arms 58 and 50 are brought into engagement with the vane since both themovements are actuated by the same shaft 49. It is possible, therefore, to free the suspension system entirely from the damping action of magnets 49 and 4! formaking other types of measurements. Accordingly, we prefer to mount both upper and lower magnets for lateral swinging movement although onlythe upper magnet 4i need be swung laterally in order to permit the plate 39 to move upwardly when arresting the motion of the vane.

From-the foregoing, it will be apparent that we have attained the objects of our invention and provided a simple, yet efficient means, for damping the pendulous movements" of a suspension system which is adapted to turn abouta substantially vertical axis in accordance with forces related to the quantity to be measured. We have also provided improved means for arresting all movements of the suspension system in order to relieve the filament from carrying the weight of the system. It is generally desirable to arrest the system whenv moving the instrument since otherwise the delicate filamentmight be broken accidentally. While We have shown ourinvntions as applied to a certain well-known type of vacuum gauge, it is, of course, obvious that our inventions could be equally well applied to other types of instruments which embody suspension systems. which are subject to vibrations which would otherwise prevent proper functioning of the instrument, This will make it possible to adapt suchgiinstrumentslfcr general and more widespread use so that delicate instruments, which have hitherto been reserved for laboratory use, may now be used with all their advantages under different circumstances. Various modifications may obviously be made without departing from the spirit of our invention as pointed out in the appended claims.

We claim:

1. In a device of the type described, the combination of a vane having an opening therein, a support, a suspension filament for suspending the vane from the support, whereby the vane is freely mounted for movement, means for lifting the vane so as to relieve the filament from supporting the vane, said means comprising a pair of spaced fingers extending within the opening in the vane, one of said fingers being selectively movable into engagement with the side of the opening whereby to lift the vane and be firmly engaged by the two fingers.

2. In a device of the type described, the combination of a vane, a support, a flexible filament suspension for suspending the vane from the support whereby the vane may swing from the support, means for damping the swinging movement of the vane, said means comprising a substantially horizontal metal plate secured to and positioned below said vane, a pair of vertically spaced magnets positioned, respectively, on opposite sides of the plate, means for selectively swinging at least the upper magnet laterally of the plate and means for arresting and holding the vane so as to relieve the filament from supporting the vane.

3. In a device of the type described, the combination of a casing, a support within the casing,

a vane, a filament suspension for suspending the vane from the support whereby the vane may swing from the support, means for damping the swinging movement of the vane, said means comprising a substantially horizontal metal plate supported by and below the vane, and a pair of magnets mounted, respectively, in opposed relation above and below the plate, said magnets being pivotally mounted for lateral movement away from the plate, means for selectively lifting the vane to relieve the filament from supporting the vane and means operable exteriorly of the easing for simultaneously moving the magnets laterally and lifting the vane whereby the latter is supported by means other than the filament suspension.

ARTHUR F. TURNER.

OSMAR A. ULLRICH, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 590,653 Thomson Sept. 28, 1897 1,126,233 Langmuir Jan. 26, 1915 1,263,393 Ellis Apr. 23, 1918 1,684,229 Koenigsberger Sept. 11, 1928 1,997,636 Gattoni Apr. 16, 1935 2,353,617 Lamb July 11, 1944 FOREIGN PATENTS Number Country Date 648,380 Germany Aug. 2, 1937 243,387 Great Britain July 15, 1926 

